Ramani Biswarathan, Ehsani Kean, Kampmann Martin
bioRxiv. 2025 Aug 12:2025.08.10.669490. doi: 10.1101/2025.08.10.669490.
Polyglutamine (polyQ) diseases, including Huntington's disease and several spinocerebellar ataxias, are caused by abnormally expanded CAG nucleotide repeats, which encode aggregation-prone polyQ tracts. Substantial prior evidence supports a pathogenic role for polyQ protein misfolding and aggregation, with molecular chaperones showing promise in suppressing disease phenotypes in cellular and animal models. In this study, we developed a FRET-based reporter system that models polyQ aggregation in human cells and used it to perform a high-throughput CRISPR interference screen targeting all known molecular chaperones. This screen identified as a strong suppressor of polyQ aggregation the Hsp40 co-chaperone DNAJC7, which has previously been shown to modify aggregation of other disease proteins (tau and TDP-43) and has mutations causative for amyotrophic lateral sclerosis. We validated this phenotype and further established a physical interaction between DNAJC7 and polyQ-expanded protein. In contrast, DNAJC7 did not modify aggregation of polyglycine (polyG) in a FRET-based model of neuronal intranuclear inclusion disease. In addition to establishing new inducible, scalable cellular models for polyQ and polyG aggregation, this work expands the role of DNAJC7 in regulating folding of disease-associated proteins.
多聚谷氨酰胺（polyQ）疾病，包括亨廷顿舞蹈症和几种脊髓小脑共济失调症，是由异常扩增的CAG核苷酸重复序列引起的，这些重复序列编码易于聚集的多聚谷氨酰胺片段。大量先前的证据支持多聚谷氨酰胺蛋白错误折叠和聚集的致病作用，分子伴侣在细胞和动物模型中显示出抑制疾病表型的潜力。在本研究中，我们开发了一种基于荧光共振能量转移（FRET）的报告系统，该系统可模拟人类细胞中的多聚谷氨酰胺聚集，并使用它对所有已知的分子伴侣进行高通量CRISPR干扰筛选。该筛选将Hsp40共伴侣DNAJC7鉴定为多聚谷氨酰胺聚集的强抑制剂，此前已证明它可改变其他疾病蛋白（tau和TDP-43）的聚集，并且具有导致肌萎缩侧索硬化症的突变。我们验证了这一表型，并进一步确定了DNAJC7与多聚谷氨酰胺扩增蛋白之间的物理相互作用。相比之下，在基于FRET的神经元核内包涵体病模型中，DNAJC7并未改变聚甘氨酸（polyG）的聚集。除了为多聚谷氨酰胺和聚甘氨酸聚集建立新的可诱导、可扩展的细胞模型外，这项工作还扩展了DNAJC7在调节疾病相关蛋白折叠中的作用。
